The lithographic production of integrated circuits, masks, reticles, flat panel displays, micro mechanical or micro optical devices and packaging devices, e.g. lead frames and MCM's may involve an optical system to image a master pattern contained on a SLM onto a wafer comprising a layer sensitive to electromagnetic radiation using for example visible or non-visible light.
Said SLM may for instance be a Spatial Light Modulator (SLM) comprising a one or two dimensional array or matrix of reflective movable micro mirrors, a one or two dimensional array or matrix of transmissive LCD crystals or other similar programmable one or two dimensional arrays based on gratings effects, interference effects or mechanical elements, e.g. shutters.
Pattern generators using spatial light modulators generally use a pulsed electromagnetic radiation source in order to project the pattern of the SLM onto the workpiece. The pulse length is typically in the range of nanoseconds and the repetition rate is typically in the range of kHz.
A problem with said pulsed electromagnetic radiation sources is that they may have a pulse to pulse energy variation or a variation in time between adjacent pulses, a so-called jitter, which may affect the critical dimension of the written pattern.